The new 6.4.0 version includes some significant changes having to do with metrics. These changes have broken core swapping. Will attach some screenshots.
For the screenshots that I will attach, I started Solr directly from the 6.4.0 download on Windows 7 (bin\solr start). Then I created a "foo" core and a "bar" core, each from a different configset, using the bin\solr command.
- Screenshot 1: you can see the two cores in CoreAdmin.
- Screenshot 2: Attempting to swap the cores, an error message appears about a metric already existing for the ping handler.
- Screenshot 3: Clicking somewhere else and then back to CoreAdmin shows that both cores have the same name – bar.
- If Solr is stopped and then started back up, the admin UI looks like screenshot 1 again – the change that caused two cores with the same name only took place within the running Solr and did not update core.properties files.